I have an unusual (I think) and very annoying problem. I can't find any info on it at all, it seems like I'm the only person in the world with this problem

The thing is, I can't put my computer in standby. Or better said, it goes into standby just fine but wakes up again right away, not even a small delay. As soon as the disks spin down, they spin up again. Other than that it's not crashing or hanging or anything, but it just doesn't want to be in standby.

I have tried pretty much everything I could think of.. Disabled all wake up stuff in BIOS, in windows disabled "allow this device to wake up the computer from standby" for everything, pulled out the network cables, all USB devices, removed the mouse and keyboard, disabled network devices, nothing works!
And the most annoying part is, like once in every 10 tries, it does stay in standby. WHY!!?

This is driving me insane! Does anyone have a clue what is going on and how I can get it to work properly?